Very little of the software I'm using handled the exceptions raised while this was happening. I checked the status page first thing, but it didn't get set to yellow for another 5 minutes after I started having problems.
The aws-s3 gem was throwing an exception correctly after a fairly long timeout ("We encountered an internal error. Please try again.")
But none of the software that was using the aws-s3 gem or causing it to be called caught the exception. I ended up with exceptions getting thrown all over the place, mostly in views from methods on data coming out of models (Rails was catching it at the top-level as ActionView::TemplateError)
I had an archive server go down because of queued up requests to send data to S3. Good lesson for us, we need to handle these types of issues better on our end.